Search found 132 matches

by ddrown
Sun Aug 13, 2017 7:01 pm
Forum: Hardware
Topic: A look inside the DS3231 RTC
Replies: 9
Views: 194

Re: A look inside the DS3231 RTC

Unless you measure 1y long you cannot get precise results (aging, temperature). I got 4secs in 6months with DS3231 (temp 19-28degC, stock reg period) - that is great as well. To go into more detail about your point about aging, this is a few months of data from two TCXOs (not the DS3231, but it sho...
by ddrown
Sun Aug 13, 2017 12:04 am
Forum: Hardware
Topic: A look inside the DS3231 RTC
Replies: 9
Views: 194

Re: A look inside the DS3231 RTC

Also the GPS 1pps outputs are not precise (especially with cheapo modules), the jitter could be huge short time. You need a quality OCXO disciplined by the 1pps output with a large time constant in the loop, like several hours or more, to get a good precision out of it.. The GPS signal can jitter 3...
by ddrown
Sat Aug 12, 2017 6:44 pm
Forum: Hardware
Topic: A look inside the DS3231 RTC
Replies: 9
Views: 194

Re: A look inside the DS3231 RTC

Unless you measure 1y long you cannot get precise results (aging, temperature). I got 4secs in 6months with DS3231 (temp 19-28degC, stock reg period) - that is great as well. That is true, aging is probably around +/-1ppm/year. And my results were under a much narrower temperature range than the ch...
by ddrown
Sat Aug 12, 2017 1:51 pm
Forum: Hardware
Topic: A look inside the DS3231 RTC
Replies: 9
Views: 194

Re: A look inside the DS3231 RTC

I spotted that. I have some of those modules on my raspis. Its actually quite an interesting device, and with a bit of tweaking is pretty accurate. I wonder how accurate you could make it with a bit of oven control and a GPS reference to tune it. No oven control, but I did get around 1 second per y...
by ddrown
Sun Jul 16, 2017 4:57 pm
Forum: IDE's
Topic: STM32CubeMX generates gcc makefiles now
Replies: 10
Views: 224

Re: STM32CubeMX generates gcc makefiles now

I used this with my latest project. It got the name of the USB middleware filenames wrong, but otherwise worked.
by ddrown
Mon Jul 03, 2017 1:54 am
Forum: Custom design boards
Topic: STM32F030 custom board
Replies: 23
Views: 2507

Re: STM32F030 custom board

I've been letting these boards run to see what happens. The TCXO's aging spec is 1ppm/year, which is about 0.083ppm/month (it's not a linear thing, but this is a decent estimation). I set the calibration on June 7th (a little less than a month ago), and it's changed in frequency by about 0.060ppm si...
by ddrown
Tue Jun 27, 2017 9:08 pm
Forum: Linux
Topic: Install STM32duino on Raspbian?
Replies: 20
Views: 477

Re: Install STM32duino on Raspbian?

Well https://github.com/rogerclarkmelbourne/Arduino_STM32/pull/283 is a ARMv7 version, I tried this one now but it gives me the following error. It's says it can't find the shared libraries but they are in home/pi/Arduino/hardware/stm/tools/linux/stlink/st-flash/lib /home/pi/Arduino/hardware/stm/to...
by ddrown
Thu Jun 15, 2017 9:43 pm
Forum: Libary request
Topic: STM32 internal temperture sensor library?
Replies: 4
Views: 185

Re: STM32 internal temperture sensor library?

There's an example under A_STM32_Examples > General > InternalTempSensor, have you tried that?
by ddrown
Wed May 03, 2017 6:28 pm
Forum: Problems with libraries
Topic: RTC Library using LSE
Replies: 19
Views: 2491

Re: RTC Library using LSE

I've been experimenting with a LSE and I have some data: https://dan.drown.org/stm32/temp-lse.png At the peak you can see it's around 78.8ppm off (around 7 seconds per day day drift). After setting the RTC's calibration, I'm getting around 70ms per day (around 0.8ppm) https://dan.drown.org/stm32/rtc...
by ddrown
Sat Apr 29, 2017 7:15 pm
Forum: Projects
Topic: free logic analizer
Replies: 21
Views: 1470

Re: free logic analizer

I posted my sump device code here https://github.com/ddrown/stm32-sump

It's based on stmcubemx and uses dma and a timer to sample the gpio.